You may have heard the rumor, or even bought into the popular belief, that taking birth control pills is causing high levels of female hormones in the environment, leading to the feminization of frogs, fish, and other aquatic species. If that is true, you might be thinking, "why doesn't the government ban birth control pills?" On the contrary, you may fear exactly that, thinking "hands off my reproductive freedom."

Well, here is a relief: a new study busts the bc pill myth. But guess who they are pointing the finger at now?Amber Wise, Kacie O'Brien and Tracey Woodruff of the Program on Reproductive Health and the Environment, University of California,San Francisco, have published a meta-study of available data, trying to get an answer to the question behind a popularly held belief:

Are birth control pills responsible for the feminization of frogs and fish?

The study performs in classic myth-buster fashion: looking at everything we know to conclude that the popular perception is false.

The authors unravel the complex range of potential triggers for the observed increases in female populations, which include the three hormones naturally found in all human urine (yes, even men contributed 12% to total estrogen excretion of the human population in a Dutch study cited by the authors). In addition to natural human sources, the synthetic estrogen (EE2) found in birth control pills and animal hormones used in hormone replacement therapies are excreted by humans. But most human waste is collected for sewage treatment, which has been found to be reasonably effective when applying modern technologies.

Conversely, animal sources of estrogen frequently enter surface waters untreated. In fact, the increasing trend towards re-using manure as fertilizer ensures direct run-off to local waters. In this regard, some findings cited in the study are quite shocking:

Veterinary use of estrogens may be five times greater than the use for oral contraceptives.

E2, one of the three natural estrogens, in human raw sewage ranges between 0.5 and 125 ng/L while animal wastes contain E2 at 30 to 2500 ng/L.

A UK study found that if only 1% of estrogens excreted by livestock reached surface waters untreated, that would account to 15% of the estrogenic activity ov those waters.

That last fact is particularly disturbing, given that even if all animals wastes are treated, 1% of the estrogens can still be expected to reach the environment, after 99% efficient waste-water treatment. If you read Brian's post on drug-resistant bacteria and CAFOs (Concentrated Animal Feeding Operations), you are probably now seriously questioning the wisdom of modern farming practices.

The authors also look at industrial sources of chemicals that can mimic the activity of estrogen hormones. Major categories of these chemicals have been banned in Europe, but remain on the market in most other countries. Plant sources also add to the hormonal activity of waters -- did you know that the soy beans beloved of many health or meat-reduction activists contain relatively high levels of phytoestrogens? Increased reliance on this source for food and/or biodiesel must take these facts into account.

The authors conclude the study with a discussion of the areas we as a society must target to reverse the disturbing trend in feminized aquatic populations. Key areas of focus include getting more waste to treatment, and improving treatment effectiveness where needed; improving the testing to target hormonally active substances in waste waters; and agricultural and chemical policy reform. While oral contraceptives may deserve some consideration, the authors specifically emphasize: "removing OCs from the market would be detrimental to women's health and their ability to decide the timing and spacing of their children and would have societal and global implications."